Large-scale domain motions of enzymes are often essential for their biological function. Phosphoglycerate kinase has a wide open domain structure with a hinge near the active center between the two domains. Applying neutron spin echo spectroscopy and small-angle neutron scattering we have investigated the internal domain dynamics. Structural analysis reveals that the holoprotein in solution seems to be more compact compared to the crystal structure but would not allow the functionally important phosphoryl transfer between the substrates if the protein were static. Brownian large-scale domain fluctuation dynamics on a timescale of 50 ns was revealed by neutron spin echo spectroscopy. The dynamics observed was compared to the displacement patterns of low-frequency normal modes. The displacements along the normal-mode coordinates describe our experimental results reasonably well. In particular, the domain movements facilitate a close encounter of the key residues in the active center to build the active configuration. The observed dynamics shows that the protein has the flexibility to allow fluctuations and displacements that seem to enable the function of the protein. Moreover, the presence of the substrates increases the rigidity, which is deduced from a faster dynamics with smaller amplitude.

No abstract

No abstract

Aim of this study is the analysis of the price responsiveness of demand for cigarettes and loose tobacco in Germany over the period 1991--2006. In this period the average consumption of all kinds of cigarettes per capita (German population > or = 15 years) declined from 634 pieces/quarter to 457pieces/quarter (-28%). Consumption of factory-made cigarettes decreased from about 545 pieces/quarter to 330 pieces/quarter in 2006 (-39%). In the same time consumption of self-made cigarettes increased from 89 pieces/quarter to 127 pieces/quarter (+42%). A one Euro Cent increase in price is associated with 28 cigarettes of all kinds consumed less per quarter. Data indicate that the different types of cigarettes are substitutes, e.g. there is evidence for a positive relationship between the price of factory-made cigarettes and the consumption of hand-made cigarettes. Thus, the increase in such consumption is rather driven by a positive cross-price effect of 17.01. Data indicate additionally an overall decrease in the cigarette consumption and a partial switch to cheaper loose tobacco. The availability of low-taxed loose tobacco may undermine the public health benefits of higher cigarette prices. Price differentials between tobacco products should be reduced in order to maximize the public health benefits of high cigarette prices.

Immunofluorescence, a powerful technique to detect specific targets using fluorescently labeled antibodies, has been widely used in both scientific research and clinical diagnostics. The probes should be made with small antibodies and high brightness. We conjugated GFP binding protein (GBP) nanobodies, small single-chain antibodies from llamas, with new ∼7 nm quantum dots. These provide simple and versatile immunofluorescence nanoprobes with nanometer accuracy and resolution. Using the new probes we tracked the walking of individual kinesin motors and measured their 8 nm step sizes; we tracked Piezo1 channels, which are eukaryotic mechanosensitive channels; we also tracked AMPA receptors on living neurons. Finally, we used a new super-resolution algorithm based on blinking of (small) quantum dots that allowed ∼2 nm precision.